Motorcyclists, race drivers, and other persons who wear protective helmets have a limited field of vision due, in part, to the helmet itself. In order to see what is occurring to the side or rear of the helmet wearer, he must turn his head to look. Needless to say, during the time his head is turned, he is unable to see what is happening in front of him. Thus, the problem of increasing the field of vision of a helmet wearer is a serious one requiring a solution both for the helmet wearer and for other persons and vehicles on the road with the wearer.
The first solutions to this problem involved mounting an ordinary mirror on the handlebars of the cycle. This solution has four disadvantages. First, the vibration of the handle bars distorts the reflected image in the mirror. Second, such mirrors generally also require the wearer to turn his or her head to see what is reflected therein. Third, the mirror cannot be used while turning the handlebar. Fourth, the area of such a mirror is relatively large, causing more drag.
There is shown in U.S. Pat. No. 3,978,526 a periscope rear view helmet and helmet adapter including a mirror optical system supported in a tunnel disposed forwardly of the frontal area of the helmet comprising a reflecting mirror for reflecting an image received from a scanning mirror positioned adjacent the crown of the helmet to a viewing mirror which reflects the images to the wearer's eyes.
U.S. Pat. No. 3,804,495 discloses a rear view reflection device for a helmet including a single reflected surface prism mounted on an upright support attached to the visor of the helmet with an adjustable mirror at the other end of the support. The mirror provides a rear view reflected sight line to the prism which is normally positioned above the normal forward line of sight of the wearer.
There is disclosed in U.S. Pat. No. 3,594,069 an integral rear view mirror face shield for use with a protective helmet. The mirrored surface is positioned below the eye level of the user and is substantially the same width as the face shield permitting a practical focal length within a relatively clean aerodynamic and compact configuration by utilizing a rearward line of sight below the maximum width of the protective helmet. Areas which are obstructed by the user's neck and the protective helmet come into view when the user turns his head. This configuration is stated as having been chosen in preference to placing a mirrored surface to the sides or above the user's eyes in order to avoid blocking his forward view and because locating the mirrored surface in this manner at a practical focal length results in a cumbersome configuration.